This invention relates to precast concrete structures placed in excavations and, more particularly, to apparatus and methods used for aligning sections of such structures during installation.
Concrete structures are placed in excavations for a variety of purposes, such as the housing of electrical and telephone equipment or as parts of storm drains and sewer systems. These structures are advantageously precast in sections to facilitate transportation from the casting facility to the installation site and are typically formed with tongue and groove mating walls which provide sealing and structural stability after installation.
In the prior art it has been common to install such structures section-by-section, first placing a floor section into a prepared excavation, placing a workman in the excavation of the floor section and lowering subsequent sections into place, as with a crane. The workman in the excavation pushes each section into place for engagement with a previously located section. These procedures often require on-site shoring of the excavation prior to placement of any of the concrete sections in order to assure that the excavation will not collapse and injure the workman. Such shoring substantially increases the labor required for installation of precast concrete structures and increases the cost of the installation. Furthermore, even such shoring does not provide sufficient safety for the worker in the excavation.